iron lll nitrate nonahydrate

[celia1]

Hi every one i need help please
I need to make 0.2 Mol of Iron lll nitrate for a yr. 12 chemistry exp:
using colorimetry to determine equilibrium constant
has anyone done this concentration ,how much nitric acid we put in and what molar also do you now if it will be colourless ?
Thanks

[whspa02]

Dissolve 80.8g of your Fe(III)nitrate in DI water containing 100mL of 2M nitric acid. Make up to 1L with DI water.
This makes an orangey brown solution.
0.002M solution is almost colourless.

[celia1]

thank you , for your reply
How do you do your 0.002mol ?
i do mine in 100ml at the time , wondering if there is a easy quicker way

[whspa02]

I make up 100mL of 0.002M on the day, just by diluting the 0.2M. It still tends to darken over the day.

[celia1]

thanks for your help one of the chemistry teacher told me both concentrations should be colourless
maybe i just add more nitric acid and see what happens

[Marama T]

I've made this in the past and it's not colourless. And if it were, how would colorimetry work?

[whspa02]

No, it's definitely not colourless.